Field of the Invention
The present invention relates to a radiographic image capturing device and a radiographic image capturing system.
Description of Related Art
Various radiographic image capturing devices (flat panel detectors) have been developed that include two-dimensional arrays of radiographic detectors and read the electrical charges generated at the radiographic detectors in response to radiation emitted from irradiators through subjects, as image data. Such radiographic image capturing devices are used in medical facilities, such as hospitals. Portable radiographic image capturing devices have also been developed and put to practical use that include casings accommodating sensor panels provided with radiographic detectors.
Similar to traditional silver halide films and computed radiographic (CR) cassettes accommodating photostimulable phosphor sheets, such a radiographic image capturing device can perform still image radiography for capturing still images (simple radiography or general radiography) by emitting radiation once and irradiating the radiographic image capturing device with radiation while the subject is disposed in front of the radiographic image capturing device.
The traditional silver halide films and CR cassettes undergo double-exposure or multi-exposure when irradiated multiple times with radiation while the subjects are disposed in front of the traditional silver halide films and CR cassettes. In contrast, the radiographic image capturing device can capture multiple radiographic images by multiple exposures with radiation with a subject disposed in front of the radiographic image capturing device, because the radiographic image capturing device can transfer the data of the captured radiographic images (i.e., image data) to external units or store the image data in a storage unit provided in the radiographic image capturing device.
Unlike traditional silver halide films and CR cassettes, the radiographic image capturing device can also capture moving images composed of consecutive frames of radiographic images (moving image radiography), such as in kymographic radiography for capturing the dynamic state of pulmonary ventilation or pulmonary blood flow of a patient having a pulmonary disorder (for example, refer to Japanese Patent Application Laid-Open No. 2004-312434 and WO2009/090894) or tomosynthetic radiography for capturing multiple radiographic images of a subject while moving the irradiator and the radiographic image capturing device.
Such moving image radiography differs from regular videography by a video camera and should be understood as a form of limited videography. The moving image radiography according to the present invention refers to the capturing of multiple consecutive frames of radiographic images that collectively appear as a moving image, and often has a frame rate smaller than regular videography, which has a frame rate of 30 frames per second, and a limited duration. In regular videography, the captured video images are usually displayed in real-time, whereas in the moving image radiography, such as kymographic and tomosynthetic radiography, real-time display of the moving images is not always supported and in many cases a moving image is not (or cannot be) displayed simultaneously with the image capturing.
The present invention is described with terms associated with video images and videography. These terms, however, do not refer to regular video images captured by video cameras and regular videography but to multiple frames of consecutive radiographic images.
For example, in kymographic radiography, pulsed radiation is emitted from the irradiator or a low dose of radiation is continuously emitted from the irradiator. In the pulsed radiation, the radiographic image capturing device usually reads image data in synchronization with the emission timing of the radiation from the irradiator, whereas in the low-dose radiation, the timing of reading of the image data is appropriately controlled for image capturing.
The radiographic image capturing device can capture still images and moving images. Thus, as known in the field of digital cameras, for example, the radiographic image capturing device may be provided with a selection switch that can be operated by the user or radiologist to switch between two radiographic modes, i.e., a still image mode for still image radiography and a moving image mode for moving image radiography. Alternatively, a signal may be sent from an external controller, such as a console, to the radiographic image capturing device to switch the radiographic mode of the radiographic image capturing device between the still image mode and the moving image mode.
In a barium meal test, for example, the subject is continuously irradiated with low-dose radiation to observe the condition of the stomach in the moving image mode, and the radiographic mode is switched to the still image mode at timings instructed by the radiologist to capture still images (for example, refer to Japanese Patent Application Laid-Open No. 2011-235006).
In the case described above, the radiographic image capturing device is switched between the still image mode and the moving image mode through operation of a selection switch of the radiographic image capturing device by the operator or radiologist or operation of an external controller, such as a console, by the operator, to send a signal instructing the switching of the radiographic mode to the radiographic image capturing device.
Alternatively, the radiographic mode of the radiographic image capturing device can be automatically switched between the still image mode and the moving image mode with a control unit of the radiographic image capturing device on the basis of radiography order information that assigns still image radiography or moving image radiography (or radiography order information that assigns the site to be captured, thereby assigning the still image radiography or the moving image radiography) downloaded to the console from an external system, such as a radiology information system (RIS), in response to an instruction from the operator or radiologist and sent to the radiographic image capturing device, directly input to the console by the operator and sent to the radiographic image capturing device, or directly input to the radiographic image capturing device by the operator.
The radiographic image device carries out the procedures for radiography corresponding to the selected radiographic mode, i.e., the procedure for capturing still images in the still image mode or the procedure for capturing moving images in the moving image mode. In either mode, the radiographic image capturing device should preliminarily identify whether the image capturing to be performed is still image radiography or moving image radiography on the basis of the operation by the radiologist or the inputted radiography order information.
For example, in the radiography performed on a patient in a hospital room or the home of a patient with a portable radiographic image capturing device and a portable irradiator, radiography performed to triage patients at an accident site or a disaster site with a portable radiographic image capturing device and a portable irradiator, or radiography performed on an injured race horse on site, the radiographic modes (still image mode and moving image mode) and the order of the radiographic modes often cannot be preliminarily selected.
In such a case, the switching operation of the radiographic modes of the radiographic image capturing device between the still image mode and the moving image mode is troublesome for the operator or radiologist. In another case, radiography may have to be promptly and continuously performed before the radiographic mode (still image mode or moving image mode) can be instructed.
Even if the radiographic image capturing device exchanges signals and data with an external controller, such as a console, via wireless communication and receives radiography order information that assigns still image radiography or moving image radiography from the controller, the radiographic image capturing device cannot maintain communication with the external controller due to an insufficient communication environment with weak signals in some cases. In such cases, the control unit of the radiographic image capturing device cannot determine whether the radiographic mode is a still image mode or a moving image mode.
In this case, the radiographic image capturing device may have a radiographic mode for performing either still image radiography or moving image radiography besides the still image mode for performing still image radiography and the moving image mode for performing moving image radiography. This mode is preferred because it allows the operator or radiologist to freely perform radiography with the radiographic image capturing device without the troublesome operation of selecting a radiographic mode or switching between radiographic modes.